Heretofore there have been many different kinds of fail safe brake mechanism provided and where the brakes have spring actuated parking or fail safe brake pressures set up therein. Typical prior art patents in this brake field include U.S. Pat. Nos. 3,638,773; 3,730,301 and 3,696,898.
In these prior braking structures, satisfactory results have been obtained in many instances. However, there is always a need for an improved, simplified braking assembly for pressure controlled braking actions and which will have fail safe characteristics but yet be provided by a mechanically uncomplicated, relatively inexpensive, sturdy braking structure.
The general object of the present invention is to provide a novel and improved fail safe type of a brake which is air actuated for normal braking action.
Another object of the invention is to provide an oil-sheer brake unit wherein primary and secondary pressure cylinders and pistons are provided and wherein braking pressure is normally produced by the primary pressure piston and the secondary piston and cylinder control the brake fail safe braking action.
Another object of the invention is to position a primary pressure piston and a secondary pressure piston in operative association with each other for independent braking action by the primary piston and for relative movement of the primary and secondary pistons.
Another object of the invention is to provide a mechanically sound, relatively uncomplicated brake which will provide good brake action over a long service life.
The foregoing and other objects and advantages of the invention will be made more apparent as the specification proceeds.